I Smell Green, You Smell Blue

In elementary school, we all learn about our five senses: taste, smell, touch, sight, and sound. Together, they continuously provide us with massive amounts of sensory input. One way we make sense of all this is by forming associations: between sights and smells, feelings and tastes, and so on. For instance, we may associate the sound of waves to the smell of the ocean, the feeling of sand between our toes, or a salty taste. But to what extent do sensory associations change based on where we are from, and to what extent are they universal? It turns out that two people from opposite sides of the globe may draw very different connections from the same stimulus. That’s according to the authors of new research published in PLOS ONE, who investigated how people from different parts of the world associate colors with smells.

The researchers divided study participants into six populations based on geographic categories: Dutch, Netherlands-residing Chinese, German, Malay, Malaysian-Chinese, and US residents. Participants smelled a series of scents—14 total, including smells like “meat,” “soap,” and “burnt”—and were subsequently asked to choose from a palate of colors which one they most closely associated with the smell.

Odor-color associations chosen by the different groups

After the experiments were performed, the researchers compared the smell-color associations of individuals within each groups, and then compared the results between groups. While people from the same geographic group tended to make similar smell-color associations, color choices differed significantly between the cultural groups. Some smell-color associations were generalizable across groups. For instance, participants who smelled a “fruity” odor largely picked a pink or red color, and people chose oranges and browns for the “musty” smells. The most similar groups to each other were the US and Germany, and the Germany and Malay samples. Overall, the Malay group’s color choices were the most different from all the others. The authors had also predicted that the geographically-close test groups would lead to similar smell-color associations, but that didn’t appear to be borne out by the data.

So, what may be happening when someone smells a scent, and then chooses a corresponding color? The authors offer several possible explanations of what could be at work:

There could be an underlying neural basis for the association of reds and pinks with fruity smells that lead people to associate the two. In other words, the associations are inherent and that’s just how our bodies and our brains work.

There could also be a statistical correspondence, which means that a particular color and smell often accompany one another. Example: “I see red and I smell fruit… perhaps the two are related.” Over time, these patterns may start to leave their mark on our brains.

Sometimes people make strong associations with colors and words (perhaps “sky” and blue), called semantically mediated correspondences. Language and how it is used can influence these associations, so this experiment was designed to use as few words as possible to minimize language-based associations.

In this particular study, the authors suggest that the variation between the different cultural groups may be evidence that color-smell associations are not inherent or universal, but are informed by other factors that could include culture, language, and experience. More work remains to better understand all the factors that influence these connections, but for now, it seems that the color of a smell may depend on where you’re from.

About Alex Theg

Alex is a Publications Manager at PLOS ONE. Born and raised in Davis, California, he lives and works in San Francisco, where he eats, lays on the beach, reads history, and spends time with his beloved pet fish.